Hot-air engine



' UNITED sTATEs PATENT oEEIoE. g

MILTON D. WHIPPLE, OF CAMBRIDGE, MASSACHUSETTS.

HOT-AIR ENGINE.

i Specification of Letters Patent No. 86,581, dated September 30, 1862.

T o all whom it may concern: Y

Be it known that I, MILTON D. VHIPPLE, of Cambridge, in the county of Middlesex and State of Massachusetts, have invented an Improved Hot-Air Engine, of which the following is a full, clear, and exact description, reference being had to the accompanying drawings, making part of this specification, in which- Figure l, is a view of the engine. Fig. 2, a vertical section through the middle of the same. Fig. 3, detail to be referred to hereafter.

My present invention relates to certain improvements in hot air engines. I am aware that a hot air engine has beenrconstructed in which the air was forced through a re in a close stove, into the working cylinder, but this necessitated the expense of a separate stove, and a loss of heat.

My invention consists, first in using the lower part of the working cylinder itself as a stove or re pot in combination with the forcing of the air from below up through the fire directly against the piston. Secondly in combination with a divided cylinder a long hollow piston fitting loosely in that part of the cylinder which is exposed to the direct eiect of the fire, and packed at its other end which is so far removed from the action of the fire that the packing will not be destroyed by it. Thirdly, in facing the end of the piston which is in immediate contact with the re by a ldisk of soapstone or other analogous fire resisting material.

lFourthly,`in combination with a hopper and the iire pot, an automatic feed for supplying the re intermittently with fuel while the engine is in operation and by which a uniform lire may be maintained proportionate Vto the work of the engine, and fifthly, in

an explosive valve in combination withethe fire chamber.

I am aware that double doors or valves have been used to pass fuel into a close fire, the outer one being closed before the inner oneV was opened, but this alone would not answer my purpose, which is not only to feed the re without opening the furnace (which would stop the engine) but also to make' the feed proportionate to the speed ofthe engine.

' That others skilled in the art may under stand and use my invention I will proceed to describe the manner in which I have carriedout the same.

the length of stroke or as Ahigh as it is ex-- posed to the direct action of the fire, is lined with fire bricks la, like an ordinary stove. An explosive safety valve G held down by spring 0 commands an opening d, made through the side of the cylinder and its lining into the fire space, this is to guard against an explosion of gas in the cylinder when the fire is first kindled and before the engine is started.

The cylinder B is divided in length into two portions, l and 2, which are held together by screw bolts e. A sheet metal belt H, or continuation of the cylinder is secured between and connects the two portions of the cylinder B, forming with the upper portion 2, a smooth continuous surface on the interior of the cylinder, but making a break in the external surface of the cylinder which tends to present the great heat of the portion l, of the cylinder from being coinmunicated to the portion 2, in which the head of the piston and its packing workwhereby the destruction of the packing by the heat is prevented.

The top of the cylinder B is open. A standard I, secured at 5 to each side of the cylinder rises above the top of it, they have each a slot f in which a cross head K, is guided. A cross brace g secures together and steadies the tops of the two standards. Two piston rods S, connect the cross head K, to the piston L. This piston consists of a head z, perforated with holes 6 and a sheet metal tube 27 of sufficient length to extend down into the part l of the cylinder B, below the top of its fire brick lining le. yW'hen the piston is at the top of its stroke, the bottom of this tube is closed by a sheet metal end m, to which is secured by a screw 7, a disk Z, of soapstone to resist the action 0f the fire with which it is in direct contact.

The tube z' fits loosely in the cylinder B, and is not intended to be in contact with it, but to run as close as practicable, the packing a, being pla-ced around the head l1., and

between it and the part 2 of the cylinder B, the packing being thus removed to a considerable distance from the fire by which it would otherwise be destroyed. The holes 1 6 in the head 7i, allow the escape of the air from the piston when it becomes heated. Two brackets Q attached to the side of the top of the cylinder B, support the bearings Vof a shaft M, to which is secured a crank N,

a rod 0, is pivoted to the end of this crank and to the cross head K. Another crank O, on the end of the shaft M, is connected by a rod 29 to a shorter crank P, on a shaft A, which is alsosupported on brackets 11, attached to the side of the cylinder B. The reciprocating` motion of the piston L rocks the shaft M, and revolves the shaft Q, which carries at its outer end beyond the side of the cylinder B, a fiy wheel R, and a cam s, (dotted in Fig. 2) the oice of which will be presently explained.

An air-pump U, is secured to the bed plate A, it has an inlet passage t, and an outlet passage u commanded by valves, the latter passage communicating by the pipe T, with.

the ash pit D, beneath the fire. This pump is operated in the following manner: A rod fu is pivoted at 8 to one of the arms of the wheel R, its other end is connected by a pin and slot at 9, to a lever w attached to a shaft V, which has its bearings on top of two standards 10 which rise from the bed A. A crank W, is attached to the shaft V, and is connected by a rod to the piston X, of the air pump U. A small pipe g/ opening into the air pipe T, enters the cylinder B, above the fire grate C. This throws a small amount of air in above the fire 'to assist in t-he combustion of the gases. An exhaust pipe Y, communicates by a passage a (shown dotted) with the interior of the cylinder B, immediately above the fire, it is commanded by a poppet valve a2, to the stem of which is attached to one end of a bent lever b2 pivoted at 12, to the side of the cylinder B, the other end of this lever rests on the cam s, and is vibrated by it as the shaft Q revolves. The stem of the valve a2, passes through a shoft arm c2 projecting from the side of the cylinder B; a coiled spring cl2 lifts the valve a2 whenever the lever b2, is allowed to vibrate by its end falling on the part 13, of the cam s which is cut away (the rest of the circumference of this cam is concentric and holds the valve a2 closed) this cam is sol formed that the valve c2 shall openy immediately before the `'piston L, reaches the top of its stroke and remain open until the piston has descended, when it is quickly closed.

I will now describe the mechanism for feeding the fuel to the fire while the engine is in operation without the necessity of opening the door E which would stop the engine and allow the escape of gas. A

stout metal pipe Z, (suiciently strong to resist the pressure of the air'in the cylinder B) is supported by a clamp e2 on the side of the cylinder, it is bent at 14 and enters the cylinder immediately above the fire, its upper part above the bend extends up Vertically and is furnished with a hopper f2 in which the coal, broken small is placed; immediately below this hopper is a valve g2 (shown detached in Fig. 3) with a cup or recess 15 cut in it, this cup receives a charge of coal and each time t-he valve is revolved this charge is emptied into the pipe Z, and falls onto the fire; the valve g2 revolves in a box 2 which communicates with the hopper f2 above and the pipe Z below but is otherwise tight; this valve is revolved by the engine in the following manner. A rod r:r is pivoted at 1G to the crank O, and is pivoted at its other end to a lever Z2 which embraces and vibrates on the stem of the valve g2. A pawl m2 on this lever engages with a ratchet wheel n2 secured on the stem of the valve g2, so that each vibration of the crank O feeds the wheel n2 one notch (the position of the pivot 16 may be changed to feed more rapidly) and each revolution of this wheel empties a charge of coal into the fire.

The following is the operation of this engine. A fire is built on the grate C, (I prefer anthracite coal), the doors E and F, are closed and secured by the screws b; the engine is started by turning the flywheel R, in the direction of its arrow by hand, this vibrates the shaft V, and operates the air-pump X (the stroke of the piston X may be varied by changing 'the position of the pivot 9, in the slot in the lever w). As the piston X descends, the air .is forced through the pipe T, into the ash-pit D and through the fire where it is heated and expanded in the cylinder B, forcing up the piston L, immediately before this piston reaches the end of its upward Vstroke the exhaust valve a2 opens t0 allow the escape of the compressed air and gases from the cylinder B through the passage z, and pipe Y; the piston L, now descends by its weight and the momentum of the wheel R, the valve a2 closing when the pislton has reached the lower part of its stroke ready for a repetition of the operation.

The bolts eV which connect the portions 1 and 2 of ths cylinder B4 are formed with shoulders to support the portion 2, or pillars may be used with bolts passing through them. Y

The valve G is not intended to prevent the accumulation of pressure within the cylinder B, beyond `a predetermined limit andy thus prevent an explosion, as in the safety valves of steam boilers, but merely to permit the escape of gas, should an eX- plosion of gases take place in the cylinder,

after first lighting the fire, and before the engine is set to Work, as sometimes occurs;

whereby the machinery might be strained and injured, if no provision was made for the escape of the gas.

What I claim is: n

l. Using the lower part of the Working cylinder itself as a stove or irepot, in combination With an air pump and passage for conveying and forcing the air from below up through the re directly against the piston, substantially as described and for the purposes set forth.

2. I also claim in combination with a divided cylinder a long hollow piston fitting loosely in that part of the cylinder which is exposed to the direct action of the fire, and packed at its other end Which is so far removed from the direct action of the fire that the packing Will not be destroyed by it substantially as set forth and described.

8. I also claim facing the end of the piston which is in immediate Contact with the fire by a disk of soapstone or its equivalent substantially as described.

4. I also claim in combination with a hopper and the fire pot of a hot air engine an automatic feed Worked from the engine and supplying the lire intermittently with fuel, substantially in the manner set forth.

5. I also claim in combination with the lire or gas chamber of a hot air engine an explosive valve G, for the purpose de scribed.

MILTON D. WHIPPLE.

Vitnesses:

THos. R. RoAcH, P. E. TESCHEMACHER. 

